Someone should make an opinionated, batteries-included JS/TS framework like Elm, based on TS, React, Flux.
Even React, Flux, Router and etc comes in several parts.
I know railties are modular but at least they come from the same project and repo and update together.
Then again Rails does let you switch out compatible parts. By compatible I mean if it adheres to "Railties", e.g. using ActiveModel for replacing Pgsql with MongoDB.